Apparatus for controlling the actuation of an accessory device in an oil pressure actuated press

ABSTRACT

An apparatus for controlling the actuation of an accessory device of an oil pressure-actuated press in such a manner that the accessory device, such as a scrap cutter, a product feed device, a product knock-out device, or an air ejector, can be actuated in a predetermined phase in the slide stroke of the press even when the stroke distance is varied. The press is of the type which comprises a pair of limit switches operable at the upper and lower limits of the stroke of a slide, the position of at least one of the limit switches being variable so as to vary the stroke distance of the slide. The apparatus of the invention constitutes a power source, a stationary variable resistance connected to the power source, a stationary contact which engages the variable resistance and is likewise connected to the power source, with the position of the stationary contact being variable in response to a change in the operative position of the limit switch of the press, a shifting contact further being disposed in engagement with the variable resistance, and Schmidt trigger circuits having inputs connected to the shifting contacts and outputs connected to a press accessory device actuating mechanism.

United States Patent [1 1 Harada et al.

[ APPARATUS FOR CONTROLLING THE ACTUATION OF AN ACCESSORY DEVICE IN ANOIL PRESSURE ACTUATED PRESS [75] inventors: Suguru Harada, Sagarnihara;

Moritaka Kuroyanagi, Tokyo, both of Japan [73] Assignee: AidaEngineering, Ltd.,

Kanagawa-ken, Japan 22 Filed: Apr. 2, 1973 21 Appl. No.: 346,908

[30] Foreign Application Priority Data Aug. 31, 1972 Japan 47-86602 [52]US. Cl 72/453, 72/22, 72/421 [51] Int. Cl B21j 13/08 [58] Field ofSearch 72/453, 22, 23, 421; 100/269 R, 256, 53

[56] I References Cited UNITED STATES PATENTS 2,782,831 2/1957 Todd72/23 2,926,497 3/1960 Biernath 72/23 3,016,005 1/1962 Tomka 100/269 R3,031,903 5/1962 Billen 72/453 Oct. 15, 1974 Primary ExaminerC. W.Lanham Assistant Examiner-G'ene P. Crosby Attorney, Agent, orFirm-Holman & Stern 571 ABSTRACT An apparatus for controlling theactuation of anaccessory device of an oil pressure-actuated press insuch a manner that the accessory device, such as a scrap cutter, aproduct feed device, a productknockout device, or an air ejector, can beactuated in a predetermined phase in the slide stroke of the press evenwhen the stroke distance is varied. The press is of the type whichcomprises a pair of limit switches operable at the upper and lowerlimits of the stroke of a slide,

the position of at leastone of the limit switches being variable so asto vary the stroke distance of the slide. The apparatus of the inventionconstitutes a power source, a stationary; variable resistance connectedto the power source, a stationary contact which engages the variableresistance and islikewise connected to the power source, with theposition of the stationary contact being variable in response to achange in the operative position of the limit switch of the press, ashifting contact further being disposed in engagement with the variableresistance, and Schmidt trigger circuits having inputs connected to theshifting contacts and outputs connected to a press accessory deviceactuating mechanism.

4 Claims, 3 Drawing Figures,

Pnemtumnswn 1 3.841.143

SEE] 1H 2 PAIENTED 1 51974 MEI e or 2 IE5 El APPARATUS FOR CONTROLLINGACTUATION OF AN ACCESSORY DEVICE IN AN OIL PRESSURE ACTUATED PRESSBACKGROUND OF THE INVENTION This invention relates generally to an oilpressureactuated press and more particularly, to an apparatus forcontrolling the actuation of an accessory device of the press such as amaterial or product feed device, a scrap cutter, a product knock'outdevice or an air ejector, for example, in such a manner that theaccessory device can be actuatedin a predetermined phase in the slidestroke even when the stroke distance is varied.

In any of the prior art oil pressure-actuated press, whenever the strokedistance of theslide is varied and- /or dies are replacedby those havingdifferent heights, the position of a limit switch or switches which areadapted to generate signals for actuating a device accessory to thepress has to be adjusted.

Such adjustment of the position of the limit switch or switches rendersthe manipulation of the press troublesome. That is, in. an oilpressure-actuated press, when it is assumed that the stroke distance ofthe slide is A or' B and the'slide moves describing the operation curveSUMMARY on THE INVENTION Therefore, one principal object ofthe presentinvention is to provide an apparatus for controlling the actuation of anaccessory device in an oil pressure-actuated press which can effectivelyeliminate the disadvantages inherent in the prior art apparatus forcontrolling the actuation of an accessory device in an oilpressureactuated press referred to hereinabove.

Another object of the present invention is to provide an apparatusforcontrolling the actuation of an accessory device-inan oilpressure-actuated press which can control the actuation of the'accessorydevice without the necessity for varing thepositiori of the-limit switchor switches even when thestroke distance of the slide is varied. y

A further object of the present invention is to provide an apparatus forcontrolling the actuation of an accessory device in an oilpressure-actuated press which can eliminate the necessity forre-positioning or, adjusting the position of the limit switch orswitches even when dies having different-heights are employed.

According to the present invention,- an oil pressureactuated'presshas'be'en provided which comprises a pair of limit switches adapted.to be operated'at the. upper and-lower limits -of the stroke of 'a'slide,'respec-. tively, for 'con'trollin'g an .oilpressure controllingelectromagnetic" valve associated :with an oil; pressureoperjatedcylinder that is adapted to operate said slide and in which;theoperative position of at. leastoneof said limit switches is v'ariablesoas to vary the stroke distanceof said slide, characterized in' thatanappara-. tus for'controlli'ng the actuation of an accessory device insaidpress-comprising a power source, a stationary variableresistance-connected to one terminal of said power source, a stationarycontact engaging said vari- 2 able resistance and connected to the otherterminal of said power source, a shifting contact in engagement withsaid variable resistance and conventional Schmidt trigger circuitshaving the inputs connected to said shifting contact and the outputsconnected to the input of a press accessory device actuation means. I

The above and other objects and attendant advantages of the presentinvention will be more readily apparent to those skilled in the art froma reading of the following description in conjunction with theaccompanying drawings'which showone preferred embodiment of the presentinvention for illustration purpose only, but not for limiting the samein any way.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the strokeof the slide in an oil pressure-actuated press;

FIG; 2 is a schematic view in partial section of onepreferred'embodiment of apparatus for controlling the actuation of adevice accessory to an oil pressureaccordance with the present inven-PREF RRED EMBODIMENT OF THE INVENTION The presentinvention will be nowdescribed by referring to the accompanying drawings and moreparticularly, to FIGS. 2 and 3 thereof which show one preferredembodiment of the invention. In F IG.'2, numeral 1 denotes the mainframe'of an oil pressure-actuated press, numeral 2 denotes the bolsterfixedly secured "to the main frame and numeral 3 denotes the slide. Asseen in any conventional oil pressure-actuated press, the boltster 2 andslide 3 have mating dies mounted thereon, respectively, which cooperatewith each other in performing a processing operation on a work piece(not shown). The slide 3 is fixedly secured to the upper end of asupport member 6; the lower end of whichhas an integral piston 5receivedinan pressure oil cylinder 4. The cylinder 4 is in threadedengagement with a worm wheel 7 at 8 and the worm wheel is rotatably=supported in a fixed position on the main frame 1. The worm wheel 7 is intum-meshing with a warm 9 which is adapted to be rotated by means of amotor 10 which is also suitably mounted on the main frame 1. When theworm 9is rotated by the motor 10 in one or the other direction, therotational movement of the worm is transmitted to the warm wheel 7 andthe worm'wheel in turn moves the cylinder 4 upwardly or downwardly oilcylinder 4 has upper and lower oil chambers 11 and l2 separated by thepiston 5 and these oil chambers are communicated through anelectromagnetic valve '15 v with 'a pressurized oil supply means (notshown) by means of oil passages Band 14, respectively.

Fixedly secured to' and horizontally extending from one side of theslide-3 (the left-hand side as seen'in, FIG;

2 .is :a support rod 16 which has a' limit switch 17 at the free orouter end for detecting the upper limit of the.

stroke of the slide 3. A substantially L-shaped support rod 18 isfixedly secured to and horizontally and: vertically from one side of thecylinder 4 the left-hand side as seen in FIG. 2 and thevertical'extension of the support rod 18 has at the upper end a platecam 19 secured theretofor detecting the upper limit of the slide strokein cooperation with the-limit switch 17 whenthe limit switch 17engagesthe cam plate as the slide reaches the upper limit of its stroke.A further support rod 20 extends horizontally from the other side of theslide 3 and has at the free or outer end a limit switch 21 fixedlysecured thereto. (The support rod 20 has an upwardly extending extensionfor thepurpose to be described hereinbelow.) The limit switch 21 isadapted to be engaged by a plate cam 22 at the upper end of a verticalsupport rod 23 or more particularly, on one of two upper extensions ofthe rod 23 for detecting the lower limit of the slide stroke, and thesupport rod 23 has an external thread on the lower end portion inengagement with an internally threaded cylindrical member 26 rotatablyreceived in a ring member 25 which is provided in the horizontal arm ofa substantially L-shaped support rod 24 which extends horizontally fromthe other side of the cylinder 4 and then upwardly. The threadedcylindrical member 26 is adapted to be rotated by a motor 27 to adjustthe position of the plate cam 22 andaccordingly, the lower limit'of theslide stroke thereby to vary the distance of the slide stroke. Theabovementioned limit switches 17 and 21 are connected to theabove-mentioned electromagnetic valve.15by

means of circuits 28 and 29, respectively and respectively control thechangeover between the rising and descending movement of the slide bycontrolling the electromagnetic valve 15 at the upper limit and lowerlimit of the slide 3, respectively.

The vertical extension 24' of the above-mentioned support rod 24 has aninwardly extending extension from which a variable electric resistanceVR suspends vertically and the resistance is adapted to be engaged onone side by a stationary-contact 30 supported on the other extension ofthe above-mentioned-cam supportrod 23. The other side of the resistanceVR is adapted to be engaged by a shifting contact 31 supported at theextreme end of the upwardly extending extension of the support rod 2(lonwhich the switch 21 is supported. The variable resistance VR andcontacts 30,31 cooperate with a power source of direct current, E inproviding an electric circuit as shown in FIG. 3 in which the shiftingcontact 31 is selectively connected to the in- I puts of a plurality ofSchmidt trigger circuits S S S S 8,, and the outputs of which areconnected to an actuation means of the press accessory device (notshown).

The above-mentioned Schmidt trigger circuits 8,, S S S, S, are,respectively, set to be operated when, for example, the inputvoltage ofthe shifting contact-31 is at 2 V, 2.5V, 5 V, 6.5 V. 8 V, respectively.These Schmidt trigger circuits are of conventional, well-knownconstruction.

Now. assuming that the stroke distance of the slide 3 is set as 200 mmby the upper and lower limit" cam plates 19 and 22, the slide 3 movesdescribing the curve a as shown in FIG. 1, the voltage at the variableresistance VR varies within the range2V 8V as the shifting contact 31shifts along the resistance VR and signal for actuating the accessorypress device are generated in the middle points a and a of the slidestroke distance, the voltage at the resistance VR is 5V when theactuation signals are generated.

vice can be easily controlled.

Therefore, when the slide 3 reaches the middle points a, and a, of itsstroke distance and the shifting contact eration at 5V generates signalsfor actuating the press accessory device.

Alternatively; in order to vary the stroke distance of the slide 3 from200 mm to mm, the threaded cylind'rical member 26 is -rotated by themotor 27 to raise the lower limit detectioncam plate 22 by 100 mm. Theupward movement of thelower limit cam plate 22 by the above-mentioneddistance inturn varies the effective resistance "value of the variableresistance VR whereby the voltage range of 2V 8V can be obtained withinthe slide stroke distance of 100 mm. Therefore, even if the slide strokedistance is varied from 200 mm to 100 mm and the slide moves describingthe curve b as shown in FIG. 1, when the slide reaches the middle points12, and b of the slide stroke distance, the Schmidt trigger circuit Sset for operation at 5V pro- .vides signals for actuating the pressaccessory device.

As clear from the foregoing, according to the present invention, evenwhen thestroke distance of the slide is varied, by simply adjusting theoperative position of the lower'limit switch, the actuation of the pressaccessory device can be simply and effectively controlled. In addition,even when it is desired to actuate the press accessory device in anydesired position within the slide stroke distance range, if the Schmidttrigger circuits are set accordingly, the actuation of the pressaccessory de- Though this invention has been-described with reference toa preferred embodiment thereof, other embodiments of this invention willoccur to those skilled in the art which are with the scope of thefollowing claims.

What is claimed is: v

1. In an oil pressure-actuated press which comprises a pair of limitswitches for operating at the upper and lower limits of the stroke of aslide, respectively, for controlling an oil pressure controllingelectromagnetic valve associated with a pressurized oil cylinder whichoperates said slide and in which the operative position of at least oneof said limit switches is variable so as to vary the stroke distance ofsaid slide, the improvement comprising an apparatus for controlling theactuation of an accessory device in said press, said apparatuscomprising a power source, a stationary variable resistance connected-toone terminal of said power source, a stationary contact engaging saidvariable resistance and connected to the other terminal of said powersource, the position of said stationary contact being variable inresponse to change in said operative position of at least one of saidlimit switches, a shifting I contact in engagement with said variableresistance and Schmidt trigger circuits having inputs connected to said6 position of said pressurized oil cylinder is vertically adjustable inaccordance with the height of particular dies employed.

1. In an oil pressure-actuated press which comprises a pair of limitswitches for operating at the upper and lower limits of the stroke of aslide, respectively, for controlling an oil pressure controllingelectromagnetic valve associated with a pressurized oil cylinder whichoperates said slide and in which the operative position of at least oneof said limit switches is variable so as to vary the stroke distance ofsaid slide, the improvement comprising an apparatus for controlling theactuation of an accessory device in said press, said apparatuscomprising a power source, a stationary variable resistance connected toone terminal of said power source, a stationary contact engaging saidvariable resistance and connected to the other terminal of said powersource, the position of said stationary contact being variable inresponse to change in said operative position of at least one of saidlimit switches, a shifting contact in engagement with said variableresistance and Schmidt trigger circuits having inputs connected to saidshifting contact and outputs connected to the input of a press accessorydevice actuation means.
 2. The apparatus as set forth in claim 1,wherein said pair of limit switches are fixedly secured to said slideand adapted to respectively close a circuit, said apparatus furtherincluding said limit switches which are engaged by cams connected to andsupported by said pressurized oil cylinder, respectively.
 3. Theapparatus as set forth in claim 2, wherein said cams and said stationarycontact are supported on support rods which are supported on saidpressurized oil cylinder, the engaging position of said cams withrespect to said limit switches being variable so as to vary the strokedistance of said slide and the position of said support rods beingvertically adjustable.
 4. The apparatus as set fortH in claim 1, whereinthe position of said pressurized oil cylinder is vertically adjustablein accordance with the height of particular dies employed.